The present invention relates to a nicotine-containing chewing gum piece packed in a wrapping of laminate.
A nicotine-containing chewing gum piece packed in a wrapping of laminate is known from blister packs, where the laminate comprises a back sheath and a front foil, typically of transparent material. Examples of blister packed nicotine-containing chewing gums are described in GB-A 2 423 757, where several sheaths are contained in an outer packet, or in WO 2007/024891, where the blister pack is enclosed in an outer member. The individual chewing gum piece is oval shaped in cross-section, a classical shape used for coated chewing gum pieces having a length of about 19 mm, a width of about 12 mm, and a maximum thickness of about 5 mm.
Nicotine-containing chewing gum is typically manufactured in this classical pellet shape, which is suitable for the coating process. Nicotine-containing chewing gum pieces can be manufactured in ball-shape, which minimizes the surface area for a given amount of chewing gum mass. Nicotine-containing chewing gums are coated either by a sweetener or by polished wax. The reason for this is that the coating or wax polish is considered necessary to provide a barrier on the outside of the chewing gum material containing the nicotine. Nicotine is a very volatile substance at room temperature, and it is a very well known problem for nicotine-containing chewing gum that nicotine evaporates from the gum material in the period from manufacture to consumption. In order to provide an acceptable shelf-life it has been considered mandatory to retard evaporation of nicotine from the gum material by on the one hand manufacturing the chewing gum piece in a shape having a small outer surface in relation to the mass of chewing gum, and on the other hand providing the chewing gum piece with the coating or wax polish that retards evaporation.
Despite these efforts, nicotine actually does evaporate from the nicotine-containing chewing gum piece prior to it being sold to the consumer. Nicotine-containing chewing gum is blister-packed, and the common blister packing has a transparent foil layer extending over the chewing gum piece to one side of the package. After shelf-storing for about half a year of wax polished nicotine-containing chewing gum it is not uncommon to observe a brownish layer on the inside of the transparent foil layer, and this brownish layer is deposited, degraded nicotine evaporated off from the chewing gum piece. In order to minimize this adverse effect and minimize the extent to which nicotine degrades into reaction products, in particular under the influence of oxygen, nicotine-containing chewing gum is normally manufactured with a hard-coating enclosing the chewing gum material. It is also known to stabilize nicotine with a cation exchange resin, such as Amberlite®. In has thus been accepted to have a loss of up to 5% of the nicotine contained in the chewing gum piece, which loss is caused by both evaporation and degradation of the nicotine prior to consumption by the user.
In addition to the problem of nicotine evaporation, nicotine-containing chewing gums are also sensible to degradation of nicotine due to influences from oxygen, moisture and light. WO 91/09731 describes packing of transdermal delivery devices for the transport of nicotine base across the skin, and in order to alleviate the problem of nicotine degradation during storage it is suggested to use a laminate having a nicotine degradation agent barrier layer in form of a metal foil, such as a foil of aluminium. According to WO 91/09731 the inner layer of the laminate must be a nicotine barrier layer, more specifically a layer of nitrile rubber modified acrylonitrile-methyl acrylate copolymer. Transdermal delivery devices for the transport of nicotine base across the skin are patches to be placed on the skin during use. Such patches typically have a low ability to retain nicotine enclosed in the patch material, at least when compared with chewing gum, which is a more stable carrier for nicotine, because nicotine is typically carried in gum base, which in itself present a barrier to nicotine evaporation.